This invention relates to the field of devices to customize substrates. Thus, the invention relates in particular to a method and/or a system to customize a substrate by depositing an additional coating (or material), commonly called “gilding” of a substrate. In particular, the invention specifically concerns a printing method comprising an ink jet printing step of a substrate followed by a “gilding” step by contact between the areas of the substrate to be gilded and a deposition device for “gilding” such as a gilding foil.
Techniques for gilding printed substrates are well known to those skilled in the art. The basic principle of this technique is based on the fact that depositing an additional coating (i.e., gilding or material) on the substrate, by a deposit “gilding” device, for example, by applying/pressing a foil (carrying said coating or gilding) on the selected areas of the substrate in such a way as to cause the portion desired of the foil to adhere to the selected areas of the substrate. For example, this technique may involve depositing the adhesive upon the substrate in a predetermined pattern before depositing the customized coating (for example, the gilding foil) on the adhesive deposited on the substrate. Depositing the adhesive may be performed using one or more techniques, such as for example inkjet printing, toner-based printing, silk-screening or offset printing.
This invention specifically concerns techniques of inkjet printing in relief, for example by means of piezoelectric printing heads, adapted according to the printing ink and/or varnish used.
The gilding foils used as part of this invention consist of several superposed films comprising by way of non-limiting example:                one optional adhesive film,        at least one gilding film,        one optional protective film,        one optional release film, and        at least one transfer layer that allows transporting the gilding foil.        
Various solutions for customization of substrate by gilding are known in the Prior Art and especially application No. WO2011110956 which, in its embodiment shown in its FIG. 2 describes a cold gilding system comprising a pressing system 200 and, upstream of this pressing system, a printing section comprising a printing device 210 (for example, an inkjet printer) for depositing a deposit pattern constituted by a layer of adhesive 222, onto a substrate 220. After pressing a foil sheet onto the substrate, the adhesive is hardened and becomes sticky, allowing the foil to adhere to the preset pattern. Pressing is performed by means of one or more pinch rollers (260) also called pressure rollers. This application of pressure is carried out on the entire gilding sheet.
Technique for gilding is typically optimized to promote better performance of the adherence of the gilding foil onto the substrate while improving the visual quality of the gilding deposited on the substrate. Despite the evolution and accuracy of gilding techniques, the Applicant has found it very difficult to reconcile these two conditions with known gilding techniques. One objective of this invention is therefore to provide a gilding technique which promotes better performance of the adherence of the gilding foil onto the substrate while improving the visual quality of the gilding deposited on the substrate.